Understanding all-optical spin switching: Comparison between experiment and theory

TL;DR

This paper reviews recent advances in all-optical spin switching, comparing experimental results with theoretical models, highlighting the reproducibility of key features, and emphasizing the need for further research to understand the underlying mechanisms.

Contribution

It provides a focused comparison between experimental observations and theoretical predictions in all-optical spin switching, emphasizing reproducible results and common features.

Findings

AOS occurs in specific magnetic samples within narrow laser parameter windows

Some samples require multiple pulses, others need a single pulse for switching

Current models are insufficient to fully explain the mechanisms behind AOS

Abstract

Information technology depends on how one can control and manipulate signals accurately and quickly. Transistors are at the core of modern technology and are based on electron charges. But as the device dimension shrinks, heating becomes a major problem. The spintronics explores the spin degree of electrons and thus bypasses the heat, at least in principle. For this reason, spin-based technology offers a possible solution. In this review, we survey some of latest developments in all-optical switching (AOS), where ultrafast laser pulses are able to reverse spins from one direction to the other deterministically. But AOS only occurs in a special group of magnetic samples and within a narrow window of laser parameters. Some samples need multiple pulses to switch spins, while others need a single-shot pulse. To this end, there are several models available, but the underlying mechanism is still under debate. This review is different from other prior reviews in two aspects. First, we sacrifice the completeness of reviewing existing studies, while focusing on a limited set of experimental results that are highly reproducible in different labs and provide actual switched magnetic domain images. Second, we extract the common features from existing experiments that are critical to AOS, without favoring a particular switching mechanism. We emphasize that given the limited experimental data, it is really premature to identify a unified mechanism. We compare these features with our own model prediction, without resorting to a phenomenological scheme. We hope that this review serves the broad readership well.